05-08-2018, 12:21 AM
Well, the 16A started to produce some unwanted noises and symptoms I didn't like after playing beautifully for several months. I decided it was time to dig into the Tobe and Sangamo molded caps. I could not find even 1 Tobe cap that measured anything reasonable on my fluke DMM. Every Sangamo measured fine (perhaps the Sangamo caps are all mica's???). I realize that the Fluke is not a perfect cap tester, but my replacement caps all measured fine with this meter. Anyway, they are replaced, the radio re-aligned ( and it did re-align better than before), and it plays again. Now we'll see if it holds up.
I have a question for the 6L6 aficionados out there. The push pull is self biased using a 210 ohm cathode resistor, 402 volt plate voltage, 277 volt screen voltage. This yields a -20 volt grid voltage with 95 ma idle current for both tubes. Most data sheets on the 6L6 talk about a grid bias more like -30 volts. These are new Solvtek tubes that I've had in my inventory for maybe 25 years. Is my idle current within reason or should I increase the size of the cathode resistor to shut the tubes down a bit? Perhaps these cheap Solvtek tubes have a bit different characteristics than original 6L6's??
Thanks for your input!
Rob
I have a question for the 6L6 aficionados out there. The push pull is self biased using a 210 ohm cathode resistor, 402 volt plate voltage, 277 volt screen voltage. This yields a -20 volt grid voltage with 95 ma idle current for both tubes. Most data sheets on the 6L6 talk about a grid bias more like -30 volts. These are new Solvtek tubes that I've had in my inventory for maybe 25 years. Is my idle current within reason or should I increase the size of the cathode resistor to shut the tubes down a bit? Perhaps these cheap Solvtek tubes have a bit different characteristics than original 6L6's??
Thanks for your input!
Rob